The subject matter herein relates generally to impedance control of an electrical connector at a mating interface between the electrical connector and a mating connector.
Some electrical connector systems utilize receptacle and header connectors to interconnect two circuit boards, such as a motherboard and daughter card. When the connectors are mated, the circuit boards may be arranged parallel to one another. Such connector systems can be complex and difficult to manufacture.
The connectors can have ground shields that are designed to shield signal contacts from other signal contacts within the connectors. During a mating operation, the ground shields of the header connector engage the ground shields of the receptacle connector and the signal contacts of the header connector engage the signal contacts of the receptacle connector. The connectors are fully mated relative to one another when mating faces of the respective housings of the two connectors abut against one another at a mating interface, blocking additional movement in a mating direction. The connectors are partially mated to one another when the ground shields and signal contacts of the two connectors are engaged but the mating faces of the housings do not abut against one another. Partial mating of the connectors may occur when, due to various aggregated tolerances in the electrical system or device, the two circuit boards are farther apart from each other than the combined length of the two connectors in a fully mated state of the connectors. For example, the two circuit boards may be fixed in place on different mounts of a chassis, and the distance between the two circuit boards may not be precisely controlled due to aggregated tolerances between various components in the system.
Although partial mating of the connectors provides an electrically conductive path that enables signal transmission between the circuit boards, the signal quality and/or signal strength may be degraded when the connectors are partially mated relative to the signal quality and/or strength when the two connectors are fully mated. For example, when the connectors are partially mated, an air gap is present along the mating interface between the mating faces of the respective housings of the connectors. Some air gaps may be present even when the connectors are fully mated, but in general the amount and/or size of the air gaps at the mating interface are greater when the connectors are partially mated rather than fully mated. The air gaps cause an electrical discontinuity. For example, the electrical discontinuity may represent an impedance spike that causes some of the electrical energy along the signal path to reflect back to the source instead of being transmitted across the connectors. The detrimental effect of the electrical discontinuity may be exacerbated at higher signal transmission speeds, such as speeds over 10 Gb/s.
A need remains for a high speed electrical connector system with improved electrical performance (e.g., electrical signal transmission) by controlling the impedance at the mating interface.